Flexion-extension gap changes during total knee arthroplasty: effect of posterior cruciate ligament and posterior osteophytes removal.

Flexion and extension gap heights were measured in 50 consecutive primary posterior-stabilized total knee arthroplasties (TKAs) to determine whether posterior cruciate ligament (PCL) release or re-establishment of the posterior condylar recess increased gap width. After PCL release, a slight symmetrical increase was noted in both gaps. In extension, gap width increased on average 1.3 mm and 1 mm in the medial and lateral compartments, respectively. The same pattern was observed in flexion, averaging 1.3 mm medially and 1.3 mm laterally. Another increase in the two gaps was observed after the posterior condylar osteophytes were removed and the posterior recess was re-established. The gaps in extension increased, with respect to the base-line value, on average 1.8 mm medially and 1.8 mm laterally, whereas flexion increased an average 2 mm medially and 2.2 mm laterally. No statistical differences were noted between flexion and extension gaps. No independent differences between the flexion and extension gaps were found in any surgical phase. Posterior cruciate ligament removal and re-establishment of posterior condylar recess does not require additional consideration in gap balancing during posterior-stabilized TKA.

Use of recombinant human erythropoietin in two-stage total knee arthroplasty for infection.

A multicenter prospective study was conducted to determine whether epoetin alfa could be used to lower transfusion requirements after two-stage exchange arthroplasty for infection. Forty-one consecutive patients undergoing successful two-stage exchange arthroplasty for an infected total knee arthroplasty were enrolled in a prospective study. Epoetin alfa (40,000 units) was administered subcutaneously after prosthesis resection and antibiotic spacer placement. Although there was no difference in the hemoglobin levels before resection arthroplasty or on postoperative Day 3 between the study group and the control group, hemoglobin levels before reimplantation were higher in the patients who received epoetin alfa (12.4 mg/dL; range, 9.3-15.1 mg/dL) compared with the control group (11.3 mg/dL; range, 8.1-14.4 mg/dL). Average increase in hemoglobin level in the interval between stages was higher in the treatment group (3.2 mg/dL; range, -0.7-6.8 mg/dL) than the control group (1.7 mg/dL; range, -1.9-6 mg/dL). The transfusion rate decreased from 83% of patients in the control group to 34% in the study group during reimplantation. In addition, overall incidence of transfusion for either stage improved from 89% in the control group to 44% in the patients treated with epoetin alfa. Perioperative epoetin alfa statistically increased the hemoglobin levels and decreased transfusion rates for patients undergoing two-stage revision for infected total knee arthroplasty.

The Insall legacy in total knee arthroplasty.

John N. Insall was a pioneer in the field of knee surgery. He was a rare individual who accomplished unparalleled levels of success as a surgeon, designer, and teacher. During the past 4 decades, he was instrumental in evolving total knee arthroplasty to its current state of excellence. Insall's impact on orthopaedics is felt by all who have come in contact with him.

Revision total knee arthroplasty: how much constraint is enough?

Revision total knee arthroplasty is a complex situation that requires meticulous technique to restore a functional outcome. The surgical objective is the same as primary total knee arthroplasty: restore the original anatomy, restore function, and provide a stable joint. To this point of stability, it is preferable to implant the prosthesis with the least degree of constraint. Therefore, in the majority of patients undergoing revision surgery, a posterior-stabilized articulation is used. However, if there is functional loss of the medial collateral ligament or lateral collateral ligament, inability to balance the flexion and extension spaces, or a severe valgus deformity, then a constrained condylar prosthesis is necessary.

Does modularity affect clinical success? A comparison with a minimum 10-year followup.

A comparison of the clinical and radiographic results of patients with metal-backed monoblock Insall-Burstein I and modular Insall-Burstein II Posterior Stabilized Knee Prostheses was done. The minimum followup was 10 years. The clinical results were comparable with a similar average Hospital for Special Surgery knee score of 85 and 84 points, respectively. Likewise, the Knee Society Knee and Functional Scores showed no statistical difference. Radiographically, the incidence of minor radiolucent lines was 11% for the Insall-Burstein I prostheses and 29% for the Insall-Burstein II prostheses, but their presence was of no clinical significance. There was no clinical or radiographic evidence of tibial component loosening with either prosthetic design and there were no revisions for polyethylene wear or osteolysis in either cohort of patients.

Revision total knee arthroplasty: planning, management, controversies, and surgical approaches.

Revision total knee arthroplasty can be a technically challenging procedure fraught with potential complications. In many cases, obtaining adequate exposure is difficult, and failure to do so can directly cause technical errors and complications. Patient-specific systemic comorbidities and anatomic details can further complicate the procedure. Careful preoperative evaluation can help to facilitate optimal results. Furthermore, specific surgical techniques help to improve the surgical exposure and can minimize complications such as wound healing problems, component malposition, and extensor mechanism disruption. All surgeons undertaking these procedures require a thorough understanding of these principles.

Accuracy of soft tissue balancing in total knee arthroplasty.

To the best of our knowledge, this is the first study to assess the accuracy of balancing of the flexion and extension gaps in total knee arthroplasty (TKA). Measurements of the heights of the flexion and extension gaps were obtained during 104 consecutive primary, posterior-stabilized TKAs in osteoarthritic patients. Clinically, all knees appeared to be well balanced intraoperatively. Rectangular flexion and extension gaps almost always were obtained within 1 mm (84%-89%). None of the knees was >3 mm from being perfectly rectangular. Equality of the flexion and extension gaps was more difficult to obtain (47%-57% were within 1 mm). With meticulous attention, perfect soft tissue balance is not always achieved in TKA.

Primary constrained condylar knee arthroplasty for the arthritic valgus knee.

The purpose of the current study was to review results of primary constrained condylar knee arthroplasty in elderly patients with genu valgum deformity. The hypotheses were: (1) constraint has no adverse effects in elderly patients; (2) treating deformity with a constrained condylar knee prosthesis in lieu of lateral ligament release avoids morbidity, particularly peroneal nerve palsy and flexion instability; and (3) press-fit noncemented stem extensions enhance fixation of the cemented core components and are not prone to loosening. Between 1988 and 1993, 44 consecutive primary Constrained Condylar Knee prostheses were implanted in 37 patients (average age, 72.7 years) with an average valgus angle of 17.6 degrees. Indications for the Constrained Condylar Knee implant were: elderly patients with genu valgum deformity and medial collateral ligament incompetence. Outcome was assessed prospectively using the Hospital for Special Surgery and Knee Society scoring systems; followup was by independent observer. Clinical and radiographic followup (average, 7.8 years) was available for 28 knees (26 patients). The Hospital for Special Surgery score improved from 52.2 to 89.6 points. The average Knee Society score and functional scores improved from 27.4 and 32.4 points to 95.2 and 67.2 points, respectively. At followup, the average alignment based on anteroposterior radiographs obtained with the patient weightbearing was 5.3 degrees. No radiographic loosening, prosthetic failures, peroneal nerve palsies, or flexion instability occurred. No failures occurred in the 11 patients (16 knees) who died before the latest followup. To the authors' knowledge, this is the largest reported series with the longest reported followup of patients with primary Constrained Condylar Knee prostheses. The use of the Constrained Condylar Knee prosthesis for elderly patients with low physical demands with genu valgum resulted in significant pain relief and improved function.

Anatomy of the epicondyles of the distal femur: MRI analysis of normal knees.

Knowledge of precise anatomic landmarks and relationships of the distal femur can be helpful in knee surgery, especially primary and revision total knee arthroplasty. We analyzed 104 consecutive routine knee magnetic resonance imaging studies to define useful landmarks and relationships. The epicondyles are described, and the relationship of the epicondyles to the joint line is defined in multiple planes. Some significant gender differences were noted. The distance from the epicondyles to the joint line correlates with the transepicondylar width of the distal femur. This information can be helpful in determining appropriate joint line position intraoperatively. The posterior condylar angle averaged 3.11 degrees for all patients, and a tendency for the posterior condylar angle to increase with age was noted, but further study of this tendency is needed.

Blood management in two-stage revision knee arthroplasty for deep prosthetic infection.

Treatment of infected total knee arthroplasty requires aggressive management to treat the infection and restore joint function. For patients with infected knee arthroplasties, a two-stage procedure is used that involves resection of the joint and placement of an antibiotic impregnated cement spacer followed by implantation of a new prosthetic 6 weeks later. Patients undergoing the two-stage procedure typically endure high allogeneic blood transfusion rates (82% to 88%) and progressive anemia because the two surgeries are spaced closely and because the infection precludes the use of alternatives to allogeneic blood. Records were reviewed of 75 patients who underwent two-stage total knee arthroplasty to characterize perioperative hemoglobin levels and blood transfusion needs in this patient group. Although transfusions were administered only when warranted by clinical symptoms and were not based on predetermined hematologic values, 62 (82%) patients received a mean of 2.3 units of blood at first-stage surgery, and 60 (80%) patients received a mean of 2.1 units of blood at the second stage. Overall, only 12% of patients did not have allogeneic blood transfusion. At the first stage before resection, mean hemoglobin concentration was 11.6 g/dL and reached a mean nadir of 8.6 g/dL 3 days after surgery. At the second stage before reimplantation, hemoglobin concentration averaged 11.1 g/dL and reached a mean nadir of 8.2 g/dL 3 days after surgery. After the first stage, allogeneic blood transfusion failed to improve postoperative hemoglobin levels enough to prevent transfusions associated with the second-stage. Patients undergoing two-stage total knee arthroplasty have anemia, and a substantial proportion of these patients require allogeneic blood transfusion at both stages. Thus, novel blood management practices are required to improve hemoglobin levels and reduce allogeneic transfusion rates in this patient population.

Revision total knee arthroplasty: a surgical technique.

The etiology of surgical failure should be defined before revision total knee arthroplasty (TKA) is contemplated, since revision surgery without a clear reason may fail to correct the underlying problem. The causes of mechanical failure include component loosening, instability, polyethylene wear, component malposition, extensor mechanism dysfunction, and loss of motion. Revision that is required because of an infection is also acomplex situation, which requires skill and meticulous technique in order to restore a functional outcome. A successful revision needs to account for ligamentous balance, bone loss, alignment, and fixation.

The posterior condylar angle in osteoarthritic knees.

The posterior condylar angle is formed by the transepicondylar axis and the tangent line to the posterior condyles. It is an important relationship to determine rotational alignment of the femoral component in total knee arthroplasty. We measured this angle directly in 107 osteoarthritic knees undergoing total knee arthroplasty. The posterior condylar angle was significantly greater in valgus knees than in other osteoarthritic knees. Given the standard deviations and ranges of values noted, the posterior condyles are potentially unreliable references for femoral component rotation in some knees.

Osteolysis associated with cemented total knee arthroplasty.

Osteolysis has not been mentioned as a complication or cause of failure of cemented total knee arthroplasties in long-term follow-up studies. We are aware of a single case report of osteolysis after cemented total knee arthroplasty. We report the case of an 87-year-old woman with massive osteolysis beneath a cemented tibial component.

Effect of nabumetone on hemostasis during arthroscopic knee surgery.

The known effects of commonly used nonsteroidal anti-inflammatory drugs (NSAIDs) on hemostatic parameters have led to concern over their use in the perioperative period. Nabumetone, unlike other NSAIDs, has little effect on collagen-induced platelet aggregation. To evaluate the effect of nabumetone 2000 mg daily on other hemostatic parameters (e.g., bleeding time, prothrombin time, and partial thromboplastin time) in the clinical setting, this double-masked study was conducted in patients with osteoarthritis undergoing arthroscopic knee surgery. After a 1-week placebo washout period, 58 patients were randomized to receive nabumetone and 53 were randomized to receive placebo. They were assessed before surgery (after 1 to 2 weeks of treatment) and again after surgery (after an additional 3 weeks of treatment). The study was designed to have 90% power to show equivalence in bleeding time to within 1.5 minutes, a difference assumed to be of no clinical importance. No meaningful differences were observed between the groups in any of the measured hemostatic parameters. Before surgery, the bleeding time increased by only 0.3 minutes with nabumetone and decreased by 0.2 minutes with placebo. The mean (+/- SD) difference between the groups in change from baseline was 0.5 +/- 0.3 minutes. After surgery, the changes were 0.1 minutes and 0.0 minutes, respectively, and the difference between groups was 0.2 +/- 0.3 minutes. These differences were neither statistically nor clinically significant, and maximum individual increases were similar in each group. Furthermore, there were no reports of abnormal bleeding in the operative knees. The results of this study show that nabumetone had little or no effect on hemostasis and suggest that this drug can be used safely in the perioperative period.